What is Shale Gas ?
Shale gas is a natural gas, composed of methane, contained in argillaceous sedimentary rocks, located between 1km and 3km underground. The main characterization of shale gas is that it is imprisoned in very compact and low permeability geologic formations.
This is why shale gas is categorized as “unconventional” gas, as it is trapped inside the rocks and cannot be exploited in the same way as gas contained in more permeable geologic formations (“conventional gas”).
Shale gas is produced in great amounts in the USA (around 12% of its local gas production in 2011), and worldwide resources are estimated to be 4 times more important than conventional gas resources. However, the lack of global research activities make it impossible to have a clear estimation of the existing and actually exploitable resources.
How is it extracted ?
In short, (you can find more details on the dedicated page of our website), shale gas exploitation requires horizontal drilling and hydraulic fracturing of deep geologic formations, a method also known as “fracking”. According to the UFIP (Union Française des Industries pétrolières), these production techniques are well known and have been used by the oil and gas industries since numerous years worldwide, and are the most adapted to the specific configuration of Shale gas deposits, even though other techniques exist at a smaller scale (link).
In order to extract the shale hydrocarbons, a vertical well has to be drilled until it reaches the bedrock (from 1500 to 3000 meters deep). Then, to free the hydrocarbons from the rock, the existing cracks can be used, otherwise crack networks have to be created. In order to do so, a mix composed of water and sand (99,5%) and chemical additives (0,5%) have to be sent with high pressure down the drilling tube.
However, the technique of fracking seems to be at the core of the controversy surrounding shale gas. It is indeed the main target of the militant movie Gasland, realized by John Fox and released in 2011. Among the problems pointed by this movie, but also press articles, anti-shale gas collectives and some scientific research reports, is that in the process of injection of the fracking fluids, thousands of vertical joints in rock strata may connect, allowing drilling fluids to seep toward the surface. The technique also requires the massive use of water, and according to a New York Times article, most of the toxic waste-water returns to the surface, sometimes with radioactive material at levels thousand of times greater than drinking water standards permit. This waste can be stored on the site in a pit or in tanks, which can leak in many ways : pond berms, pipes, liners may fail. Heavy rains can also cause ponds to overflow. Also pointed as a risk of pollution is the fact that when the gas goes up the well, the first batches are vented into the atmosphere rather then captured, which might represent a substantial source of greenhouse effect emissions.
As the UFIP notes, there appears to be no proof to incriminate the technique of fracking in itself, and as they argue, pollution problems may come from the lack of means of small exploiting structures (in the case of the USA), allowing for defaults in the cementing of the well, for instance. This elements would replace the debate around the “technicity” of the implementation of fracking rather than on the technique itself.
Still according to the UFIP, all of these techniques have been constantly improved, regarding the control of their implementation, the integrity of wells and the isolation of drilling tubes. Moreover, the horizontal drains enable to avoid the multiplication of wells on the surface, avoiding then the degradation of landscapes.
What problems does it imply ?
Prospective studies have shown that France remains highly and durably dependent to other countries regarding hydrocarbons. Natural gas plays an important role in France, as it is more and more substituted to carbon and fuel, which have a more important greenhouse gas emission footprint.
As a consequence, Shale gas is considered one of the main energetic and economic stakes for the future energy mix in France.
Quantitatively speaking, the only information the government disposes for the time being, in order to determine its energetic policy, is the results of the studies from the International Energy Agency, which estimates the technically recoverable french resources at 5 Tm3 (which corresponds to 90 years of our current consumption). According to a report of the CGIET (Conseil Général de l’Industrie de l’Energie et des Technologies) and the CGEDD (Conseil Général de l’environnement et du Développement Durable), we can take the hypothesis that 50% of the surface of the permits could be actually exploitable (excluding urban, inaccessible, protected and unadapted zones), the effectively recoverable resources would be of 500Gm3, that is to say 10% of the IEA’s estimations. Both of these hypothesis are coherent, but both also lack of precision.
However, even though the situation in France regarding shale gas exploitation is only at its first steps, the research operations have provoked strong reactions, with local demonstrations and protestations from environmental organizations since the end of 2010. We can consider two categories of actors here, characterized by the strong incomprehension between them. On the one side, we have the industries who have operated for decades, and see the “non conventional” resources in the continuity of their long experience, and to which environmental rules represent substantial constraints. On the other side, the public is struck by how suddenly the shale hydrocarbons took center stage, and the lack of information, consultation and pedagogy from the government and the oil companies led to a strong mistrust from local populations.
These concerns gave way to a series of parliamentary debates, ending with the promulgation of the law n°2011-835 on July, 13th, forbidding the exploration and the exploitation of hydrocarbon mines implying hydraulic fracturing techniques.
This lead to a moratorium of the controversy for the time being, as the decision was taken before the mandated Commission could make its conclusions and expertise regarding the technique of “fracking”.
These elements lead us to ask one question : Can shale gas be a viable, eco-friendly component of the future energy mix in France ? Should the debate be reopened ?
- What role can shale gas play in the future energy mix in France ?
- How climate friendly is shale gas ?
- Why and how does water contamination matter in the controversy ?
